iPhone + iPad bundle deal question

I will try to make this as easy to understand as possible since my brain is fried trying to figure it out since I haven't been on a 2-year contract in forever.

I currently have a family plan with 2 iPhones and 2 iPads. 1 phone and iPad are on Next currently. The other phone and iPad are paid off and haven't been upgraded (a 6 and an Air 1).  

I am interested in the current promotion, which is to get any iPhone on Next and get an iPad Mini 2 32GB for $99 on a 2-year agreement. (https://www.att.com/shop/wireless/devices/iphone-ipad-bundle.html)

My question is this - when I go through the motions to order and select the 2-year agreement option for the iPad to get the discount, it says that:

• By upgrading to a 2-year wireless contract, you will not be eligible to receive the Mobile Share Value monthly discount of $15 on plans lower than 10GB, or $25 on 10GB or higher plans.

I have a 10GB Mobile Share Value plan for these lines. So is the deal not as good as it might seem at first glance? In order to save $200 on the price of the iPad (it's normally $299 with a 2-year contract) will I be paying an extra $25 a month now for 2 years ($600) since one of my devices is now on contract and I've lost the discount?

In a perfect world I would love if AT&T allowed down payments on iPads like they do for iPhones so I could sell my current iPad and use that money to lower monthly Next payments for the new iPad, but they don't seem to allow that.